Wire tensioning device



1950 w. R. HUNTY 2,534,130

' WIRE mnsronmc ngvrcs Filed Dec. 50, 1949 Inventor: William R. Hunt-His Attorney.

Patented Dec. 12, 1950 WIRE TENSIONING DEVICE William R. Hunt, FortWayne, Ind., assignor to General Electric Company, a corporation of NewYork Application December :0, 1949, Serial a... 130,053

This invention relates to wire tensioning devices of the type used tomaintain constant tension on a wire during coil winding operations.-

In the design of machines for high speed winding of coils, for exampletransformer coils, it is desirable to maintain constant tension on thewire during the winding operation. In such machines rapid changes in thespeed of the wire are encountered and the inertia of the supply spooland the wire causes forces to be exerted on the wire which may causeundue stretching and breaking unless a constant predetermined wiretension is maintained. Furthermore, high inertia forces in tensiondevices formerly utilized tend to vary the tension on the wire to theextent that the wire is stretched and cold worked to an excessivedegree. Copper wire has an elastic limit and when bent beyond thislimit, it becomes harder and stiffer. Wire which has been hardened andstiffened by bending or cold working will not lie as flat as the wirewhich has not been coldworked and consequently the layers of cold workedwire in a coil take up more space than in a coil formed of very soft andductile wire. In addition, wire passing through ordinary wire tensioningdevices may become stretched reducing the diameter. The elastic limit isexceeded when the wire is bent more than a certain angle. Whenever wirepasses over a pulley or idler wheel, as on a tensioning device, it isbent twice, once when it goes on the wheel and once when it comes on thewheel. It is the radius of the wheel which is important and not theangle of contact between the wheel and the wire since once the wire hasbeen bent to conform to the contact of the wheel, it bends no more untilit again leaves the wheel. Thus, if the direction of a traveling wire ischanged through 180 by passing it over two pulleys which each bend at90", it is cold worked twice as much as if it were bent through 180 bybeing passed over a single pulley. It is therefore desirable in thedesign of a wire tensioning device to keep to a minimum the number ofdirection-changing pulleys over which the wire passes and that suchpulleys be of relatively large diameter in order to avoid cold workingof the wire.

An object of this invention is to provide an improved wire tensioningdevice.

Another object of this invention is to provide an improved wiretensioning device wherein the wire is not cold worked.

A further object of this invention is to provide an improved wiretensioning device in which the wire is passed around only a singlewheel.

Claims. (Cl. 242-455) Furtherobjects and advantages of this inventionwill become apparent and the invention will be better understood fromthe following description referring to the accompanying drawing, and thefeatures of novelty which, characterize this invention will be pointedout with particularity in the claims annexed to and forming a part ofthis specification.

In accordance with this invention, there is provided a light weight lowinertia spokeless ring of relatively large diameter around which thewire is passed. Three idler rollers engage the inner surface of the ringto provide rotatable support therefor, two of the rollers being mountedon a stationary member. The third roller is mounted on one end of alever arm which is in turn pivotally mounted on the stationary member. Aspring acts on the lever arm to urge the third roller against the ringto provide rolling friction thereon and to tend to deform the ring froma circle to a triangle. An idler pulley is mounted on the other end ofthe lever arm and bears on the wire leaving the ring. Increased tensionon the wire leaving the ring acts on the idler pulley to cause the leverarm to move against the spring so that the third roller applies lesspressure on the ring. This reduces the rolling friction on the ring andalso allows the ring to tend to return to its circular shape permittingit to rotate more freely. Conversely, decreased wire tension allows thespring to urge the third roller against the ring applying more pressureso as to increase the rolling friction and to increase the deformationof the ring.

In the drawing Fig. 1 is a side elevation view of the improved wiretensioning device of this invention and Fig. 2 is a cross section viewtaken along the line 2-4 of Fig. 1.

Referring now to Fig. 1, there is shown a light weight deformablespokeless ring i of relatively large diameter having a groove 2 formedin its outer periphery. A pair of fixed idler rollers 3 are mounted on aspider 4 in a suitable manner, as for example by studs 5. The rollers 3are pref erably mounted on antifriction bearings as at 6. The spider Iis in turn secured to a stationary frame member I in any suitablemanner, as by studs 8. A third antifriction bearinged idler roller 9 isprovided mounted on a movable lever arm III by a stud II and the leverarm I! is in turn pivotally mounted on the spider member 4, as at 12.The fixed rollers 3 and movable roller 9 engage the inner surface of thering I, which may be rubber faced, as at l3, to provide a rotatablesupport for the ring I. An antifriction bearing mounted idler pulley I4is mounted on the other end of the pivoted lever arm III by a stud I5. Aspring I 6 is held in compression between the lever arm I and anextension portion ll of the spider member 4 and serves to bias the leverarm III to urge the movable roller 9 against the ring I to providerolling friction on the ring. In addition, the pressure applied by themovable roller 9 by virtue of the spring I6 tends to deform the ring Ifrom a circle toward a triangle. A set screw I8 in the end of theextension H of the spider member 4 is provided to adjust the pressureapplied on the ring I by the movable roller 9.

The wire I9 from a supply spool (not shown) is wrapped around the ring Ione and one quarter times and the wire leaving the ring I passes underthe pulley ll. The wire 20 is deflected slightly from a straight line bythe pulley I4 due to the loading of the tensioning spring I6. As thetension on the wire 20 leaving the ring I is increased, the wire 20tends to straighten,

causing the pulley I4 to move the lever I 0 against the spring I6reducing the pressure on the ring I applied by the roller 9. This allowsthe ring I to tend to return to its circular shape and the reduction inrolling friction also permits the ring I to turn more freely.Conversely, a decrease in the tension of the wire 20 leaving the ring Ipermits the spring I6 to move the lever arm III to increase the pressureapplied on the ring I by the roller 9. This not only increases therolling friction, but, as pointed out above, tends to deform the ring Ifrom its original circular shape further increasing the friction effectused for tensioning the wire. A pressure type tensioner ZI applies aslight initial tension to the wire I9 entering the ring I so as to holdthe wire on the ring I.

It, can be readily seen that the inertia in this device is reduced to aminimum since the pulley or ring I around which the wire passes does nothave spokes or a hub. Furthermore, the wire is passed around only asingle pulley and, therefore, cold working of the wire is avoided. Inthis connection, it has been found that for ordianry sizes of wire theradius of the ring I should be at least 4 inches to insure that the wire20 leaving the ring is ductile.

It will now be readily apparent that this invention provides anextremely simple device for maintaining constant tension on a wire andfurthermore, since this device utilizes a single low inertia relativelylarge diameter ring, around which the wire is passed, cold working ofthe wire is prevented thus facilitating coil winding. While three idlerrollers are shown, it will be readily understood that a different numbermay be used, for instance four with two fixed rollers and two movablerollers.

While I have illustrated and described a particular embodiment of thisinvention, modifications thereof will occur to those skilled in the art.I desire it to be understood, therefore, that this invention is not tobe limited to the particular arrangement disclosed, and I intend in theappended claims to cover all modification which do not depart from thespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A wire tensioning device comprising a spokeless ring adapted to havesaid wire passed therearound, a plurality of idler rollers engaging theinner surface of said ring for rotatably supporting said ring, at leastone of said rollers being mounted on one end of a movable lever arm,resilient means for urging said one roller against said ring providingrolling friction thereon, and an idler pulley mounted on the other endof said lever arm and adapted to bear on the wire leaving said ringwhereby increased tension on said wire causes said one roller to applyless pressure on said ring permitting said ring to turn more freely.

2. A wire tensioning device comprising a spokeless ring adapted to havesaid wire assed therearound, a plurality of idler rollers engaging theinner surface of said ring for rotatably supporting said ring, at leastone of said rollers being movably mounted, resilient means -for urgingsaid one roller against said ring providing rolling friction thereon,and means responsive to the tension of the wire leaving said ring forincreasing or decreasing the pressure applied by said one roller.

3. A wire tensioning device comprising a relatively large diameterspokeless ring adapted to have said wire passed therearound, a pluralityof idler rollers engaging the inner surface of said ring for rotatablysupporting said ring, at least one of said rollers being mounted on oneend of a pivotally mounted lever arm, spring means acting on said leverarm to urge said one roller against said ring providing rolling frictionthereon, and an idler pulley mounted on the other end of said lever armadapted to bear on the wire leaving said ring whereby increased tensionon said wire causes said lever arm to move against said spring causingsaid one roller to apply less pressure on said ring permitting said ringto turn more freely.

4. A wire tensioning device comprising a relatively large diameterspokeless ring adapted to have said wire passed therearound, a pluralityof idler rollers engaging the inner surface of said ring for rotatablysupporting said ring, at least one of said rollers being mounted on oneend of a lever arm pivotally mounted on a stationary member, theremaining rollers being mounted on said stationary member, spring meansacting on said lever arm to urge said one roller against said ring forproviding rolling friction thereon, and an idler pulley mounted on theother end of said lever arm adapted to bear on the wire leaving saidring whereby increased tension on said wire causes said lever arm tomove against said spring so that said one roller applies less pressureon said ring permitting said ring to turn more freely.

5. A wire tensioning device comprising a relatively large diameterspokeless ring adapted to have said wire passed therearound, three idlerrollers engaging the inner surface of said ring at equally spacedintervals for rotatably supporting said ring, two of said rollers beingmounted on a stationary member, the third of said rollers being mountedon one end of a lever arm pivotally mounted on said stationary member,spring means acting on said lever arm to urge said third roller againstsaid ring providing rolling friction thereon, and an idler pulleymounted on the other end of said lever arm adapted to bear on the wireleaving said ring whereby increased tension on said wire causes saidlever arm to move against said spring so that said third roller appliesless pressure on said ring permitting said ring to turn more freely.

6. A wire tensioning device comprising a spokeless low inertiadeformable ring adapted to have said wire passed therearound, aplurality of idler rollers engaging the inner surface of said ring forrotatably supporting said ring, at least one of said rollers beingmovably mounted, resilient means for urging said one roller against saidring providing rolling friction thereon and tending to deform said ringfrom a true circle, and means responsive to the tension on the wireleaving said ring for increasing or decreasing the pressure applied bysaid one roller.

7. A wire tensioning device comprising a spokeless low inertiadeformable ring adapted to have said wire passed therearound, aplurality of idler rollers engaging the inner surface of said ring forrotatably supporting said ring, at least one of said rollers beingmounted on one end of a pivotally mounted lever arm, resilient means forurging said one roller against said ring providing rolling frictionthereon and tending to deform said ring from a true circle, and an idlerpulley mounted on the other end of said lever arm adapted to bear on thewire leaving said ring whereby increased tension on said wire causessaid one roller to apply less pressure on said ring permitting said ringto turn more freely and allowing said ring to tend to return to acircular shape.

8. A wire tensioning device comprising a relatively large diameter,spokeless, low inertia deformable ring adapted to have said wire passedtherearound, a plurality of idler rollers engaging the inner surface ofsaid ring for rotatably supporting said ring, at least one of saidrollers being mounted on a pivotally mounted lever arm, spring meansacting on said lever arm to urge said one roller against said ringproviding rolling friction thereon and tending to deform said ring froma true circle, and an idler pulley mounted on the other end of saidlever arm adapted to bear on the wire leaving said ring wherebyincreased tension on said wire causes said lever arm to move againstsaid spring so that said one roller applies less pressure on said ringpermitting said ring to turn more freely and allowing said ring to tendto return to a circular shape.

9. A wire tensioning device comprising a relatively large diameter,spokeless, low inertia deformable ring adapted to have said wire passedtherearound, a plurality of idler rollers engaging the inner surface ofsaid ring for rotatably supporting said ring, at least one of saidrollers being mounted on one end of a lever arm pivotally mounted on astationary member, the other of said rollers being mounted on saidstationary member, spring means acting on said lever arm to urge saidone roller against said ring providing rolling friction thereon andtending to deform said ring from a true circle, and an idler pulleymounted on the other end of said lever arm adapted to bear on the wireleaving said ring whereby increased tension on said wire causes saidlever arm to move against said spring so that said one roller appliesless pressure on said ring permitting said ring to turn more freely andallowing said ring to tend to return to a c'ircular shape.

10. A wire tensioning device comprising a relatively large diameter,spokeless, low inertia deformable ring adapted to have said wire passedtherearound, three idler rollers engaging the inner surface of said ringat equally spaced intervals for rotatably supporting said ring, two ofsaid rollers being mounted on a stationary member, the third of saidrollers being mounted on one end of a lever arm pivotally mounted onsaid stationary member, spring means acting on said lever arm to urgesaid third roller against said ring providing rolling friction thereonand tending to deform said ring from a circle to a triangle, and anidler pulley mounted on the other end of said lever arm adapted to bearon the wire leaving said ring whereby increased tension on said wirecauses said lever 'arm to move against said spring so that said oneroller applies less pressure on said ring permitting said ring to turnmore freely and allowing said ring to tend to return to a circularshape.

WILLIAM R. HUNT.

No references cited.

